This month’s article focuses on the portion of a submersible water system between the wellhead and the house. To put things in perspective, let’s think about what needs to happen in this area to make the system work …




This month’s article focuses on the portion of a submersible water system between the wellhead and the house. To put things in perspective, let’s think about what needs to happen in this area to make the system work. We’ll need some pipe to get the water from the wellhead to the tank, and then into the house. We’ll need to provide some sort of control for the pump to turn on and off, and a check valve between the tank and the wellhead to prevent the tank from draining back into the well when the pump shuts off. We’ll need to have a pressure gage to know how the system is performing, and a pressure relief valve to protect the system in case the pump controls fail and the system starts to build too much pressure. Finally, we’ll need a drain valve to drain the tank for servicing. Figure 1 shows the component layout for a system with a pre-charged pressure tank.

Setting the Tank

The pressure tank needs to sit on a solid surface. If it is in a basement or garage with a concrete floor, no additional support is needed. If it is outside, some sort of solid pad will be needed. Most pump wholesalers carry either plastic or lightweight pre-cast concrete appliance pads that can be easily carried to the job site and that are much easier to install than pouring a pad. They particularly are useful if you are in an area where freezing is not a problem, and the tanks are installed outside where you do not need a big pad for a pump house.

The pressure tank also needs to be accessible for servicing. Today’s pre-charged captive air tanks are built to last 10 years and longer, but they eventually will need to be replaced, so make sure you leave room to get the tank out.

Plumbing the Pressure Tank

The decision as to what type of piping to use – PVC, galvanized steel or copper – depends on local codes and personal preference. I like galvanized steel or copper because either one is stronger and is less likely to be broken if someone kicks it or drops something on it. Many pump installers use PVC in the pump house, and it works fine as long as it is protected. It is much faster and cheaper to install. Check your local codes to make sure that the type of plumbing you plan to use is approved.

System Isolation Valve

In order to be able to service the system without having the water in the house drain back when the plumbing at the tank is opened up, it is a good practice to install a gate valve or ball valve on the house-side of the tank tee. Make sure the isolation valve is on the house-side of the PRV and never put an isolation valve between the PRV and the pump.

Finally, you will want to install a union at the wellhead to allow the pump to be pulled without having to cut pipe when it comes time to service the pump.

Next month, we will be talking about the basics of how pumps work. ’Til then ….

ND

Tank Tee or Fabricated Tank Connection

Some installers fabricate the tank connections out of galvanized fittings. My preference is to use one of the specialized stainless steel, lead-free brass or galvanized tank tees offered by the water well accessory manufacturers because they eliminate five or six joints that could leak, and they save time.

For future serviceability, be sure to install a union between the tee and the tank – or on both sides of the tee – so that when it comes time to replace the tank, you don’t have to cut out your old plumbing.

Whether you use a prefabricated or cast tank tee – or make your own – you need to provide four outlets for the following: 1⁄4-inch tap for a pressure gage, 1⁄4-inch tap for a pressure switch, 1⁄2- or 3⁄4-inch tap for a pressure relief valve (PRV), and a 1⁄2- or 3⁄4-inch tap for a drain valve. You can get a tank tee that has a union going to the tank and all of these taps included, or you can get one with just the larger taps for the PRV and drain, and a check valve with taps for the gage and pressure switch. Or you can make the whole thing up with galvanized fittings; it’s your choice.

Pressure Relief Valve

The purpose of having a pressure relief valve is to protect the system – and the people and property in the vicinity of the system – from damage, should something go wrong and the pump builds up too much pressure. The most common failure that can cause the system to over-pressurize is for the pressure switch to stick in the “on” position. Remember that some submersible pumps – particularly those designed for deep wells – are capable of producing hundreds of pounds of pressure. I have seen pictures of a pump house roof blown off when a pressure tank exploded because the pressure switch stuck and there was no PRV on the system. Always install a pressure relief valve, and always make sure it is large enough to handle the output of your pump. A 1⁄2-inch PRV is not large enough to protect a 55-gpm deep-set pump.

Check Valves

It is necessary to install a check valve between the tank and the well to prevent the contents of the tank from draining back into the well when the pump shuts off. Depending on the depth of the well, you will have at least one additional check valve in the well, as we discussed in earlier articles, but it still is a good practice to install one aboveground where it is more accessible, and provides additional assurance that the water in the tank will not drain back into the well. A check valve at the tank also helps to minimize the possibility of water hammer as the pump cycles on and off.